Pilonidal sinus is a chronic inflammatory disease of the skin and subcutaneous tissue. The term “pilonidal” was used for the first time by Richard Manning Hodges at the end of the 19^th century, and was coined from Latin words pinus (hair) and nidus (nest). This was a Latin description of a disease that resembled a nest of hair (1). The mechanism of the formation of a cyst associated with hair penetration into the skin was described in 1992 by George E. Karydakis (2). The disease is accompanied by three main factors: a penetrating hair, penetrating force and susceptibility of the skin, with the likelihood of the disease being a quotient of these three elements. Hirsutism, hyperhidrosis, Caucasian race and poor hygiene are factors favouring frequent occurrences of this disease. Men develop it more often (3). Deeper gluteal cleft caused by obesity also predisposes to the disease (4). Pilonidal sinus is typically located in the gluteal cleft (5). In the world publications, there are reports of the disease at other, often distant locations, e.g. in the suprapubic area (6), armpit (7), foot (8), penis (9), umbilicus (10), eyelid (11), clitoris (12), intermammary cleft (13), nose (14), or scar after removing a Tenckhoff catheter (15). Usually, it is human hair that causes the formation of pilonidal sinus, but the literature also reports cases caused by animal hair in people who shear sheep (16, 17). There is no other Polish publication describing pilonidal sinus of animal origin. The article presents a case of atypical pilonidal sinus caused by animal hair, located between the fingers of the patient who is professionally involved in shearing dogs.